Troubleshooting BGP

Troubleshooting BGP is not an art, nor a science, it's straightforward methodical verification of each layer of functionality. Skip something and you'll be sitting on the phone for hours with tech support.

1. Learn TCP/IP and know it COLD
2. Learn BGP and know it COLD
3. MEMORIZE the BGP Best Path Selection Algorithm
4. Know the common causes of Problems
   • Impatient BGP administrator
   • No TCP/IP connection
   • Bad Access Lists
   • Bad Route Filters
   • Advertised Network Unreachable
   • Synchronization
5. Troubleshooting Techniques
   • Use the appropriate BGP Commands for troubleshooting
     • show ip route
     • show ip bgp (regex)
     • show ip bgp longer-prefixes
     • show ip bgp neighbor
   • Route Servers
     • Memorize a few addreses
     • Use them to check your routes as heard outside your ISP's network.